Posted
by
Zonk
on Saturday February 11, 2006 @04:48PM
from the best-part-about-space-travel-is-you-can-leave dept.

DrStrabismus writes "PhysOrg has a story about research that may indicate that close to light speed travel is possible. From the article: 'New antigravity solution will enable space travel near speed of light by the end of this century, he predicts. On Tuesday, Feb. 14, noted physicist Dr. Franklin Felber will present his new exact solution of Einstein's 90-year-old gravitational field equation to the Space Technology and Applications International Forum (STAIF) in Albuquerque. The solution is the first that accounts for masses moving near the speed of light.'"

You do realize we nearly have light speed weapons? Lasers. One of the benefits is that for practical purposes flight time from weapon to target is zero. No more having to lead the target. It makes interception of fast moving things far more practical.

Theres no point in travelling at close to light speed if your have no way of stopping....SPLAT

Well, considering that the nearest star systems are greater than 4.3 light years away [ucsd.edu], you do not have to worry about it, as you would be dead from starvation.

It's the same reason that Nuclear subs are not limited by how much time they can stay underwater, but how much food they can carry. The need for food makes such long distances impractical, if not intolerable. "Growing" food along the way would mean a very limited diet for eight years (assuming you want to come home), something else that is intolerable.

The first use of this could be unmanned probes - but a four year wait time for signals to travel means that it would be impossible controlling it, and would have to have it's own artificial inteligence.

Of course, if you just wanted to visit the Mars and breath its clean fresh air and gaze upon its deep green pastures then this...oh wait...Mars doesn't have that.

I think the best way to travel long distances is by using a stargate. Mondays on the sci-fi channel.

Well, considering that the nearest star systems are greater than 4.3 light years away, you do not have to worry about it, as you would be dead from starvation.

If the vehicle travels close enough to the speed of light, the trip will take just months, weeks, or even days for those onboard. Near light-speed travel is a great way to conserve life-support resources for long trips.

Surely time dilation effects would significantly lessen the amount of air and food that needs to be carried?

Yes, that was exactly my point. There's another odd effect caused by near light-speed travel: If you fly straight at an observer at near light-speed, the observer sees you approaching faster than the speed of light. This is, of course, an illusion, but an illusion that affects all measuring devices (e.g., radar, eyes, telescopes, etc.). This happens because your ship is following very closely

If you were headed right at someone at the speed of light, you would just seem INCREDIBLY blue-shifted (more energetic). You would not, ever, at any time, seem to be moving faster than light.

If a person is travelling at substantial portions of light speed they will experience time dilation. People moving at near the speed of light would experience, say, a 4.3 LY trip at high speed as, perhaps, several months, but an outside observer would, from whatever position they were standing, see the trip as taking at a minimum 4.3 years + whatever extra time was needed because the ship was slower than light.

You seem to be confusing time dilation (an effect on those moving at high speed) with... well, actually, nothing - you just seem to think it applies to all parties, which is not the case.

Yes you would be incredibly blue-shifted, but you would in fact appear to be coming in faster than light:

Suppose I fire a missile at you from 10 light-seconds away. If the missile is travelling at 90% of the speed of light, it'll take just over 11 seconds to hit you. You'll see it 10 seconds after I fire it, and the missile itself reaches you 1 second later. From your perspective, it looks & feels as though that missile was travelling at nearly 10 times the speed of light.

And he's right, in that yes, sometimes things CAN appear to be moving faster than light at first calculation. I don't think it would work exactly as he described with an object coming straight at you, however.

To an observer, the minimum time for another object to move from a point to another a light-year away is one year, yes; that's what makes c invariant. However, for the object moving, experinced time goes down asympotically as the speed of light is approached. If you were moving at c, you would experience literally no passage of time on the trip to Alpha Centauri from Earth, even though it would take you 4.3 years to an observer on Earth.

Another way to state it is that from the perspective of someone moving near the speed of light, the distance from Earth to Alpha Centauri shrinks; with the distance shorter, of course it takes less time to travel. However, the distance is still the same to the observer on Earth, and so the time for the trip as viewed by the observer is much longer.

(By the way, this is part of the reason why nothing can go faster than the speed of light; the distance between two points can't shrink to less than zero.)

This difference in space-or-time from different perspectives is why the theory is called relativity; space and time are not absolute constants for everyone evverywhere, but always exist relative to your reference frame.

"An example of this is NASA's James Hansen. He speaks out directly to the public and is mobbed by his peers as a result. More power to him."His peers DID NOT MOB HIM. Bush's fundamentalist political appointees are suppressing scientists all over the spectrum (as you know, of course). On global warming, reproduction, evolutionary biology, space science. Fundamentalist overseers and corporate lobbyists are running the show at all the agencies.

"Everthing else [in science] is simply theory. Which is based on some authority and never allowed to be questioned."

Wrong, wrong, wrong, and a thousand times wrong!The whole basis of science is that everything is open to question. There are few things more prestigious in science than to refute a previously accepted theory. Ever heard of a guy named Albert Einstein? Yeah, thought you might have. Used to be that Newton's theories were the accepted way in which the universe worked, but Einstein showed differently.

The main reason it seems like some theories are "unquestionable" is simply because most of the ways in which people choose to challenge them have been shown time and time and time again to be false.If you get 100 people a day proposing a design for a perpetual motion machine using a series of cogs, wheels, and magnets, you're not going to take the time to explain to each and every one why their design won't work, instead, you're just going to tell them to bugger off and leave you alone.

Of course, scientists are human, and at times they will reject things inadvertently which they shouldn't. However, if you think you have a good explanation as to how/why we can, in fact, travel faster than the speed of light, instead of whining to Slashdot about how stuck in the mud scientists are, why not publish it? You'd be the next Einstein!

Replying to my own post, as I forgot to mention something else, and Slashdot's "edit post" button has undergone a total existence failure...

The parent also mentioned that scientific theory is based on authority. This is utter nonsense. Authority counts for nothing in science.

We accept Einstein's theories as being correct. Why? Because he was a really smart guy, and therefore must have been right? No. Because he showed exactly how and why his theories were correct.

If I tell you that water turns to ice or steam sometimes, and that's the way it is, because I say so, and because I'm smarter than you, then you'd probably tell me to get stuffed (and rightly so)

On the other hand, if I tell you that cooling water to 0C causes it to freeze into ice, and heating it to 100C causes it to boil, giving off steam, then you can try for yourself in your own kitchen. It doesn't matter if you think I'm a genius or a raving lunatic - it doesn't even matter if I actually AM a raving lunatic. The only thing that counts is whether it works or not. And the things we accept in science are those that work - and if we don't know, we run with our best current explanation based on the avaliable data until a better one comes along.

That's the wonderful thing about science. It's perfectly possible for some unknown, uneducated nobody with a bright idea to overturn hundreds of years of accepted science.

(of course, it's also rather unlikely, as the simple fact is the vast amount of unknown, uneducated nobodies who try to do that are completely off the mark, and don't have the first clue what they're talking about... doesn't mean it can't happen though.)

Time Dilation doesn't actually help much here. You have to accelerate to high speed and deccelerate at the end of the journey. Human beans can handle high accelerations for brief times with few ill affects, but we're talking months here. I suppose if you remain strapped into a squishy chair without having to move around too much then two or three g's might be more reasonable, but I'm pretty sure noone's done the studies.

Anyhoo, I typed "relativistic acceleration" into google, and two clicks later I was h [ucr.edu]

I've read somewhere that if you could maintain 1G of acceleration - speeding up for half the trip and then turning around and decelerating at 1G for the other half - you could basically reach anywhere in the universe within a normal human lifetime because of time dilation effects.

Actually the probability of hitting a star, much less a planet, is pretty low since space is pretty empty. However, what's much more troublesome are huge gas clouds or just the plain intergalactic medium since travelling near the speed of light means that those particles will hit your spaceship at relativistic speeds which is not very healthy to humans or electronics. Even worse, all light gets blue-shifted a LOT. Harmless visible light gets shifted into the x-ray spectrum and x-rays get shifted into really

The forces reducing a human travelling near the speed of light to a greasy patch on the back of the spacecraft. From TFA:

Felber's antigravity discovery solves the two greatest engineering challenges to space travel near the speed of light: identifying an energy source capable of producing the acceleration; and limiting stresses on humans and equipment during rapid acceleration.

Well, we have no problem running around in 1G for our whole live...So weeks or months of acceleration wont hurt at all... in fact they would act as a convinient way of creating "artificial gravity" on the ship.

And even 1G adds up after a few days, and in a matter of a few months you are _highly_ relativistic.

According to linear calculations of what it takes to get relativistic, it will take about 2 years under 1 G acceleration to reach the speed of light.However, this is actually an underestimate since relativistic effects make it harder to get that close to the speed of light, the closer you get. If you could achieve a constant 1G, that is how long it would take, but this is physically impossible since effective mass increases with velocity.

Because if you have to accellerate for an entire year to get above the 57% the speed of light he's talking about, there's a lot more time/distance you have to go through where you are likely to run into a piece of sand that is gonna do just nasty things to your spaceship. Once you are above that 57% cuttoff, you have a nice antigravity field clearing your path (according to him).

What if, after you have been accellerating for months, but are still at only 50% the speed of light, you hit a 1 lb chunk of rock/dust/ice that fell off some asteroid...

50% of speed of light = 1.5 x 10^8

1 pound = 0.4536 kg

Kinetic energy = (.5) (mass) (velocity) (velocity)

Kinetic energy = (.5) (.4536 kg) (1.5 x 10^8) (1.5 x 10^8)

Kinetic energy = (5.1 x 10^15)

Ouch.

The energy of the atomic bomb dropped on Hiroshima was only ~ 5.2 x 10^13

Even hitting a piece of sand at half the speed of light is gonna do waaaaaay more than just scratch your paint job. You want to get to get up to speed where you have the antigravity-clearing path for you as soon as possible, because every second going less than that speed is extremely dangerous. (That's if his theory isn't entirely bogus.)

I'm guessing, at that speed, the rock will just pass through your ship creating a nice cylindrical hole. Any thoughts?

From the point of view of the rock, all that would happen is that a solid object inside that spaceship is going to create a nice cylindrical hole in the nonmoving rock.

Come on, even a few electrons in vacuum that slam into a solid target at a velocity of c/2 (about 10^5 eV) will generate loads of X-rays by kicking out electrons that are in the deepest shells inside the atoms. With heavier

Light-speed travel is impossible, but near-light-speed travel is wildly impractical, because of the mass you gain. This guy seems to be saying that if you have an anti-gravity machine, you could counteract that. You couldn't get to FTL, but you could go a lot faster than without it. Heck, there's all KINDS of nifty things you could do with an anti-gravity machine.And if my grandmother had wheels, she'd be a wagon.

I think that this guy has been pushing his anti-gravity solution of general relativity for a

This guy seems to be saying that if you have an anti-gravity machine, you could counteract that.

Nonono: he's saying that a mass travelling near the speed of light creates an "antigravity beam" in front of it. This sounds hokey, but it's not unprecedented - frame dragging is a similar situation where general relativity basically says that a moving body can "push" others nearby. So in this case the near-light-speed object is "dragging" its frame forward. Calling it an "antigravity beam" sounds wacko, but it's probably quite straightforward. It's almost like the objects would be riding the "wake" of the NLS object, caused by the fact that the object is moving faster than space can respond.

He's essentially saying that you can pretty much effortlessly accelerate something to really high velocities with little effort by hitching a ride on a bigger object.

(Where to find a star moving at greater than.577c is another question.)

Well, there's something about "Mach's Principle" that I don't believe has ever been untangled. But I think that only applies to rotational velocity. (I.e., what makes you think you're rotating rather than still?) I think he asserted, approx., the entire rest of the universe dragged your frame. Mach's Principle [thefreedictionary.com]

Personally I'm a bit skeptical about his claims, however energy appears to be conserved. This method uses gravitationally-mediated kinetic energy exchange - this is the same principle that allows gravitational slingshot [wikipedia.org] to work.

I think you have good reason to be skeptical, I'm not convinced this guy isn't a crank. Anybody can post a paper on a preprint server. Does he have any papers on this subject that have actually made it into a peer reviewed journal?

Also this story is basically based on a press release from Starmark, the company that this so-called "noted scientist" founded himself, so basically he wrote the press release I'm guessing.

Also the fact that he's giving a talk at a conference means nothing, I've been to plenty of conferences where they let a few cranks give talks. I sat through a talk on Creation and the Big Bang at a Astrophysics conference once and the guy was a loon.

That said the biggest proof that this guy could be a crank is the fact that this story got posted on Slashdot, where something like 90% of the science stories are crap.

If I am reading this correctly (IIARTC), there is no way to safely stop with any foreseeable technology. If the anti-gravity wave reduces to near nothing, as you approach near nothing speed, than you have to be pretty damned sure that you aren't bumping into the satellite for Alpha Centauri news when you near it.
With unchartered space, a collision is bound to happen when you slow down unless your sensors can detect something oh say the size of a buick from 1,000,000 miles ahead when you tap the brakes.

Buick? You mean the size of a dust mote. If a dust particle weighs 1/100 of a gram, and you are going roughly the speed of light, the kinetic energy of the dust particle relative to you (assuming that the dust particle is roughtly standing still) is

Thats 4.6 Hydrogen Bombs of energy that the dust particle has relative to you. Do you want to collide with 4.6 Hydrogen Bombs? I don't think that NLST is practicle, even if it turns out to be possible. What we need is a way to simultaniously transport stuff.

You make the assumption that the dust mote would actually stop,
only then would the bulk of the KE go into the target space ship. More
likely is that since the KE of each atom in the dust mote
is so much larger than the atomic bond energy holding the
grain together, the dust mote to the spacecraft really behaves
like a very densely packed bundle of cosmic rays. If the
spacecraft walls don't stop individual particles of that
energy (ie like cosmic ray protons) then it won't stop the
dust particle. The atoms would go in one side, out the
other radiating a small fraction of their relative energy
as gamma rays as cherenkov radiation and compton radiation.
The dust would go out the other side as a diverging cone shaped
spray of plasma.

Umm.. everytime you move you are time traveling. When you run, time is moving slower for you, and so on. Take something the mass of Jupiter, cram it into a very thin spherical shell with an 8-foot diameter or so, sit inside it and come out a year later and you'll see time has advanced decades in comparison to your one year. We know how to time travel, but traveling far distances is hardly feasible (and traveling backwards still only works on paper).Regards,Steve

Why is an exotic solution involving anti-gravity even necessary, when there's the Bussard ramjet [wikipedia.org]? While certain versions of this concept are infeasible, there's plenty of room for technical improvement. The ramjet has been a mainstay of science fiction for decades such as in Larry Niven's Known Space [amazon.com] universe, precisely because it seems the solution closest to actual development.

Bussard ramjets are just cool and fine, and i liked the idea, too.But the physics dont work out.

You get at most 2% or so of the mass converted into energy by the fusion process, even if you could fuse everything together perfectly efficient. But once your spaceship is moving quite fast (more than 10% or so of the speed of light), you will need to use more energy to move and collect the particles in your flightpath than you could possibly get by fusing them together.

Felber's research shows that any mass moving faster than 57.7 percent of the speed of light will gravitationally repel other masses lying within a narrow 'antigravity beam' in front of it.

because, of course, no physical phenomenon can operate only for masses travelling above a fixed speed like that because such a phenomenon would violate Lorentz invariance. Therefore he's not actually using Einstein's equations which are fully Lorentz invariant. Note that I'm making weak assumptions here - I'm not even assuming the validity of Einstein's field equations, I'm just saying that this work doesn't follow from the equations he claims it follows from. That means he's made up some new physics, something completely untested, and is therefore a crackpot.

That means he's made up some new physics, something completely untested, and is therefore a crackpot.

Truly unique concepts are always met with opposition. There is a quote that I love (don't know the source) "Don't worry about having a unique idea stolen, if it's truly unique you will have to beat them over the head with it."

I'm not saying I support grandparent, I'm just saying that your comment is anti-science. Just because someone has a new idea does in no way make them a crackpot... most (if not

You are completely missing the point even though I was at great pains to spell it out. He claims his deductions are from Einstein's equations. This is impossible. Therefore he has made up new physics. Anyone can make up new equations. Absolutely anyone. This isn't new science at all. Look, I can do it. I think I'll say F=ma^1.0002 and show how I can use this to violate conservation of energy and generate free power for all. You can't just make up new equations to solve an engineering problem unless you have

That's true, he didn't, it came from the formula E=MV^2 that was found by a French woman dropping steel balls into clay, it was a correction to Newtons erroneous E=MV. The C is just a constant V, Einstein got the idea because of experiments around the time had shown the puzzling result that light travels at the same speed in all directions.

Now when Einstien published his paper he assumed it was all just a mathematical curiosity, he did not think it translated to t

because, of course, no physical phenomenon can operate only for masses travelling above a fixed speed like that because such a phenomenon would violate Lorentz invariance.

No. (For one thing, Cerenkov radiation is a physical phenomenon that operates only for masses travelling above a fixed speed.)

All this is saying is that if you've got an object (say object A) at rest, and another object (say object B) approaching object A at more than 0.577c in object A's reference frame, object A will be pushed forward (away from object B). Obviously if object A and object B are aligned exactly, they'll collide - but if object A is off-axis from object B, it will be "pushed along" with object B.

Since the relative velocity is measured in one object's rest frame, it's Lorentz invariant. (Object B sees object A approaching it at 0.577c, and sees object A pushing object B backwards).

It's very similar to frame dragging, actually. With frame dragging, there is likely a "critical rotational velocity" above which an object near the rotating object will be forced into an orbit. There's probably a "critical rotational velocity" above which an object deflects every incident object away from it.

And as with frame dragging, it likely exists for lower velocities - but the "push" is probably not along the axis of object A's direction, which means it won't "push" the object along.

While antigravity is a cool SciFi story device, it is quite possible that attempting to implement an antigravity device is like pulling yourself out of the swamp by pulling at your own hair like Munchhausen, or like protecting yourself from rain by sitting in an open boat on a lake.

Now even when Dr. Felbers calculations are true, you'd first have to find a star speeding at a speed of 57%+ of lights speed(or accelerate one yourself:-P), then you'd have to get in front of it, and in order to avoid the star smacking right into your spaceship, you'd have to have a speed of 0.57c already. Moreover(guessing), when you'd accelerate over 0.57c to take advantage of it, as you move away, the antigravity cone probably would loose focus and dispel just like gravity with a spread function of 1/r^2, quickly rendering it useless unless you'd just float along with the star.

it is quite possible that attempting to implement an antigravity device

You're not building an antigravity device. The star acts as an 'antigravity' device, which is a crappy name for it anyway. Just think of it as "forward frame dragging". If a massive object travelling close to c moves close to you, it drags your frame of reference violently along with it. You're "riding its wake."

Now even when Dr. Felbers calculations are true, you'd first have to find a star speeding at a speed of 57%+ of lights speed(or

Put some money in a stock index fund then climb aboard your spaceship. Accelerate to near-light speed and take a cruise of some nearby solar systems for a few hundred years. Come back, having aged little, and collect your fortune.

One of the fundemental principles of logic is that you can not reduce the credibility of an argument by reducing the credibility of the one posing it.

In other words, 2+2 is not any more valid when posed by the pope than by Hitler. Or to go less concrete, Relativity would have been no more or less likely if Hitler has proposed it rather than Einstein.

Judge the good doctors ideas on their merits rather than on his merits.

The density of interstellar space is about one atom per cubic centimeter [hypertextbook.com].
If the spaceship were going near the speed of light (3 x 10^10 cm/sec), it would be hit by 3 x 10^10 relativistic particles per cm^2/sec. This is about the equivalent of one Curie [wikipedia.org] per cm^2, which would kill a human and cripple any electronics on board

A very heavy magnet could deflect the protons, but the neutral atoms would be unaffected by the magnetic field.

Felber's research shows that any mass moving faster than 57.7 percent of the speed of light will gravitationally repel other masses lying within a narrow 'antigravity beam' in front of it. The closer a mass gets to the speed of light, the stronger its 'antigravity beam' becomes.

Moving faster than 57.7% of c? Relative to what?

Right now, the earth is moving through space at a speed greater than 57.7% relative to something. No, I don't know what, or where, but rest assured there's some body out there somewhere in whose frame of reference the Earth is moving at greater than 57.7% of c. And there's some other body in whose frame of reference the Earth is moving at greater than 10% of c, and another body where Earth is moving at 95% of c, and another body where Earth isn't moving at all (Hey, like me!).

So why isn't the Earth emitting such an antigravity beam, repelling masses in its path? Rest assured that if it were, we'd be seeing its effect, like ferinstance as it played havoc with GPS satellites.

Or, heck, there are cosmic rays which occasionally smack into the Earth's atmosphere at a speed that's only infinitesimally smaller than c in Earth's FOR. They should *definitely* be emitting some sort of antigravity, if this guy's correct. Should be trivial to observe, but we haven't seen it.

... and becuase c is constant you can't compare your speed directly to the speed of light or to space itself (i.e. the "aether" which was disproven by the Michelson-Morley experiment). Your speed is not an absolute number but is only defined *relative* to other objects. Therefore it's difficult to have an effect which kicks in when travelling above a certain speed, because from other frames you appear to be travelling at different speeds and so different observers would expect different values for the eff

Ok, I've worked in gravity for a while, but unfortunately I haven't time right now to go through this guy's paper [arxiv.org]. Several things are setting off my B.S. detector, though.

First, this guy is not a "noted" physicist, let alone a noted gravitational physicist, as far as I can tell. He published some papers [stanford.edu] in accelerator physics while affiliated with the Naval Research Lab. He has no publications, or as far as I can tell, training in general relativity. He's now affiliated with some company ("Starmark, Inc.") in San Diego. Furthermore, gravitational physicists generally give talks at gravity conferences (or at least physics conferences), not space engineering conferences (which have drastically lower standards when it comes to gravity, since the organizers of the conference typically have no GR background).

Second, I skimmed the preprint of his (unpublished) "antigravity" paper. He claims that a distant observer watching a particle fall into a black hole, in the (initial, local) rest frame of the particle, will see the black hole to approach the particle, and then cause the particle to accelerate away from the black hole. This is not in any weird "warp drive" spacetime, but in ordinary Schwarzschild spacetime — such as the spacetime outside of a star or a planet (!). Yes, you read that right, according to him, even planets create antigravity (if you're traveling fast enough). This bears no relation to anything I know about orbits of particles in Schwarzschild spacetime.

Then he mentions performing a Lorentz transformation of a particle trajectory into the frame of a distant observer. This is impossible. You can only apply a global Lorentz transformation to a flat (Minkowski) spacetime, not a curved spacetime (such as Schwarzschild). Well, you can apply a transformation to a flat tangent space at a point in a curved spacetime, but you can only transform a vector in the tangent space at that point, not an entire trajectory that spans a continuum of points. It is true that Schwarzschild geometry is asymptotically flat for "distant" observers, and he's speaking of transforming into the frame of a distant observer, but the fact remains that you cannot Lorentz transform a worldline that is not entirely within an approximately flat region of spacetime (and his trajectories definitely aren't always far from the gravitating body).

Now, you're free not to buy my suspicions, because as I said I haven't the time to go through all his calculations and see what's up (general relativity calculations are a pain in the ass). My bet, however, is that he's simply misinterpreting a coordinate quantity as having physical meaning. This is a common error for GR beginners (and you can see a prime example of it in the crackpot A. Mitra, who claims that black holes contradict the Einstein field equations based on his misinterpretation of coordinate derivatives in Schwarzschild spacetime). The thing about GR is that you can write solutions in any coordinate system you want, and you have to make sure that the quantities you're calculating are physically meaningful, and not just an artifact of whatever coordinates you happened to choose. Anyway, that's my guess based on what this guy has written so far and the kind of errors I see people make when making "wild" claims in GR. But it's also possible he simply made a math error. I am not betting, however, that he has suddenly discovered antigravity lurking within the ordinary Schwarzschild metric.

No, we have reduced to the problem of how to accelerate only part of the ship, while the other parts can hitch a ride on the first. I suspect the sweet spot would be the first part at 2/3 of the total mass.

No, we have reduced to the problem of how to accelerate only part of the ship, while the other parts can hitch a ride on the first. I suspect the sweet spot would be the first part at 2/3 of the total mass.

If you're correct, then we're done:

To accelerate the ship to near light speed, we just need to figure out how to accelerate 2/3 of the ship to near light speed.

To accelerate 2/3 of the ship to near light speed, we just need to figure out how to accelerate 4/9 of the ship to near light speed, and use it to accelerate the 2/3 part.

To accelerate 4/9 of the ship to near light speed, we just need to figure out how to accelerate 8/27 of the ship to near light speed, and use it to accelerate the 4/9 part that we'll use to accelerate the 2/3 part we'll use to accelerate the whole ship.

...skipping a bunch of steps...

To accelerate an unimaginably teny tiny bit of the ship to near light speed, we just need to figure out how to accelerate an even smaller bit of the ship to near light speed; we'll use a flashlight.

You have to know the exact cause of gravity to negate it. Last time I checked they dont know what exactly adds to the weight of a single atom so I dont see how they can create antigravity.

What complete and utter nonsense. While I doubt I will see working antigravity in my lifetime (or if it is even possible at all), the idea that you must "know the exact cause" of something to manipulate it effectively is rubbish. Electromagnetic fields were not well explained until many decades after they had been suc

Ah ha. I see. May I be the first to volunteer you for the most incredible ride of your life? Or the shortest. We're not really sure. Game?

Provided this theory turns out to be mathematically sound, then yes, please do sign me up. There is nothing I can conceive of that I can accomplish on this world that compares with the chance to see the stars - even if it means no return trip.

If you travel fast enough you can get as far as you like in as short a time as you like. There's an effect called time dilation. Maybe you haven't heard of it?

Have you every tried to compute the distance you can cover assuming a constant acceleration of, say, a tolerable 2G. The distance you can get in a time t in your own frame of reference grows exponentially (well, hyperbolically cosinusoidaly which is much the same thing) with t because of time dilation. When you've mastered the physics required you m

Near light speed travel is a prett cool achievement, but it's completeley useless, here's why: We can't go faster than light (the speed of light is the maximum speed of "things in the universe" light just happens to travel that fast, simply because it can't go any faster). But even at light speed th closest galaxies are still years away, so we really can't 'go anywhere'

There are approximately 100 billion stars in our galaxy... all of these stars less than 300000 light-years away. I'd say that's pretty

No. The problem is not the distances per se, it's the need for engines that don't need to carry all their fuel/reaction mass for the whole trip.A ship accelerating at 1g half way to alpha centuri, then decelerating on the second half of the trip can get there in less than 10 years as perceived by the travellers. The problem is that no known engine system, with the possible exception of a Bussard Ramjet, could power the ship. In the age of sail sea voyages often lasted 5 years or more, just because we now

This is wrong. As observed from Earth, it would take over 1000 years to travel to somewhere 1000 light years away. But for passengers travelling close to the speed of light, distances in the direction of travel are relativistically contracted, so it would take much less time. Provided we don't mind all our friends being long-dead when we return, the speed of light is not a limit on reaching distant stars.

I'm not familiar with Dr Felber, so I researched a little. The referenced news item is actually a PR release from Felber's company, Starmark. Could it be part of an attempt to later have credibility when trying to secure a grant to develop his idea? As such, it seems more commercial than academic.

But interestingly, when I researched "Franklin S. Felber", I found conflicting dates for his degrees. At USC it says M.A. Physics, 1973; Ph.D. Physics, 1975. http://physics.usc.edu/Alumni/F.html [usc.edu]. But the Universi

You may be right. But you ought to consider the implications of travelling faster than light which include time travel. I'm pretty confident in that implication because it follows from a model that fits lab experiments where accelerating particles to near lightspeed are commonplace.